7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Justin Chen [ Upstream commit 7c0b82d087908765c6c7daeb06943e21b78d523e ] On API v1/v2 boards, the DCPU coprocessor can steer kernel readl_relaxed() and writel_relaxed() to any address within 256 MB of the ioremapped DPFE dmem or regs base. The DCPU firmware provides a 28-bit offset which the driver adds to the ioremap base without any bounds checking in get_msg_ptr(). This allows a compromised DCPU firmware to trick the host kernel into reading or writing arbitrary memory-mapped I/O registers in vmalloc space. When combined with a root-writable sysfs file like dpfe_refresh, it provides an arbitrary MMIO write primitive. Similarly, world-readable sysfs files can be used to leak other devices' register contents. Fix this by recording the resource_size() of the dmem and regs ioremaps at probe time, and rejecting any offset that, along with the largest field accessed (DRAM_VENDOR_ERROR + sizeof(u32)), exceeds the recorded mapping size. Fixes: fee5f1ef6cf7 ("memory: brcmstb: dpfe: support new way of passing data from the DCPU") Cc: stable@vger.kernel.org Signed-off-by: Justin Chen Assisted-by: Gemini:gemini-3.1-pro-preview cursor Signed-off-by: Danesh Petigara Reviewed-by: Florian Fainelli Link: https://patch.msgid.link/20260826201500.3000125-2-danesh.petigara@broadcom.com Signed-off-by: Krzysztof Kozlowski Signed-off-by: Sasha Levin --- drivers/memory/brcmstb_dpfe.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/drivers/memory/brcmstb_dpfe.c b/drivers/memory/brcmstb_dpfe.c index 08d9e05b1b338..66343205f585b 100644 --- a/drivers/memory/brcmstb_dpfe.c +++ b/drivers/memory/brcmstb_dpfe.c @@ -182,6 +182,8 @@ struct brcmstb_dpfe_priv { void __iomem *regs; void __iomem *dmem; void __iomem *imem; + resource_size_t regs_size; + resource_size_t dmem_size; struct device *dev; const struct dpfe_api *dpfe_api; struct mutex lock; @@ -401,9 +403,14 @@ static void __iomem *get_msg_ptr(struct brcmstb_dpfe_priv *priv, u32 response, */ switch (msg_type) { case 1: + if (DCPU_MSG_RAM_START + offset + DRAM_VENDOR_ERROR + + sizeof(u32) > priv->regs_size) + goto bad_offset; ptr = priv->regs + DCPU_MSG_RAM_START + offset; break; case 0: + if (offset + DRAM_VENDOR_ERROR + sizeof(u32) > priv->dmem_size) + goto bad_offset; ptr = priv->dmem + offset; break; default: @@ -415,6 +422,12 @@ static void __iomem *get_msg_ptr(struct brcmstb_dpfe_priv *priv, u32 response, } return ptr; + +bad_offset: + dev_err(priv->dev, "DCPU returned out-of-range offset %#x\n", offset); + if (buf && size) + *size = sprintf(buf, "ERROR: DCPU offset out of range\n"); + return NULL; } static void __finalize_command(struct brcmstb_dpfe_priv *priv) @@ -858,6 +871,7 @@ static int brcmstb_dpfe_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct brcmstb_dpfe_priv *priv; + struct resource *res; int ret; priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); @@ -869,17 +883,21 @@ static int brcmstb_dpfe_probe(struct platform_device *pdev) mutex_init(&priv->lock); platform_set_drvdata(pdev, priv); - priv->regs = devm_platform_ioremap_resource_byname(pdev, "dpfe-cpu"); + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dpfe-cpu"); + priv->regs = devm_ioremap_resource(dev, res); if (IS_ERR(priv->regs)) { dev_err(dev, "couldn't map DCPU registers\n"); return -ENODEV; } + priv->regs_size = resource_size(res); - priv->dmem = devm_platform_ioremap_resource_byname(pdev, "dpfe-dmem"); + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dpfe-dmem"); + priv->dmem = devm_ioremap_resource(dev, res); if (IS_ERR(priv->dmem)) { dev_err(dev, "Couldn't map DCPU data memory\n"); return -ENOENT; } + priv->dmem_size = resource_size(res); priv->imem = devm_platform_ioremap_resource_byname(pdev, "dpfe-imem"); if (IS_ERR(priv->imem)) { -- 2.53.0